Roller bit



Sept. 3, 1940.

H. C. SMITH ROLLER BIT Filed Oct. 19, 1958 IN VENTOR,

2 g A TTORNE Y Patented Sept. 3, 1940 UNITED STATES A PATENT OFFICE 1 Claim.

This invention relates to roller bits.

An object of the present invention is the provision of a rotary drill wherein certain of the cutters are held in such a position that stress on 6 said cutters is directly communicated to the body of the drill and in this manner, if the body of the drill is built so as to have considerable resistance to movement, the cutters are at all times maintained in a given position during a drilling l operation, to the .end that the cutters perform their function in a most efiicient manner.

By way of illustration, I might state that in the present invention the drill pin, so called, upon which a pair of cutters may be mounted, is

at an angle to the axis of the drill body. In ordinary parlance, I may say that the drill pin is bent at a slight angle at a median zone thereof, and a pair of drill cutters carried upon the drill pin. Any excessive weight upon the cutters is communicated to the bent pin, and as the pin has its ends rigidly secured to the drill body, any tendency to create a bending movement in the pin is directly resisted not only by the pin but by its connection with the drill body, to the end a that all stresses that would tend to bend the pin are absorbed by the drill body.

In actual practice, I have found that the pin will maintain its form under the most severe operating conditions and the cutters will funcao tion in a proper manner. These cutters are so arranged on the drill pin that they rotate easily.

Due to the construction of the drill, its simplicity and arrangement of parts, the drill is relatively inexpensive to manufacture with a consequent lowering in the selling price thereof, may be easily assembled and disassembled, and it has been found to perform the function required of it in an eflicient manner.

With the above mentioned and other objects in view, the invention consists in the novel and useful provision, formation, construction, association, and relative arrangement of parts, members and features, all as shown in a certain embodiment in the accompanying drawing, described generally, and more particularly pointed out in the claim.

In the drawing:

Figure 1 is a fragmentary vertical sectional view of the improved roller bit, and,

50 Figure 2 illustrates one of the legs of the bit body.

Referring now with particularity to the drawing, the improved roller bit is designated as an entirety by the numeral I, and the same includes 55 a body 2 having a pin end 3, the pin end having the usual tapered threads 4 and central bore 5. The body is provided with four equidistantly spaced-apart legs, three of which are shown in the drawing at 6, I, and 8. The legs 6 and 8 are opposed and terminate in such a manner as to provide inwardly directed slots 9 having beveled edge portions l0 bounding the slots. Adapted to be interposed between the said legs 6 and 8 and received within the slots 9 of both said legs is a pin II. This pin is bent at its median zone so as to provide what may be termed a bent pin construction, but more accurately stated as having two portions Ila and llb, the axes of which cross at a median zone at a slightly obtuse angle.' For the purpose of illustration and not as limitation upon the invention, it may be said that this angle is approximately 2 /2 degrees relative to a horizontal line. I may further express the idea by stating that planes passed through the axis of each pin portion Ila and l lb would be at a dihedral. Ends of the pin II are tapered or conical in shape, as illustrated at l2 and I3.

Adapted to be carried on the portions Ila and II b are roller cutters I4 and I5. These roller cutters are conventional in form and adapted to best fit on the pin with anti-friction means between the pin and the rollers. Taking one of the rollers by way of example, say the roller I5, it is formed with a pair of races I6 and I1, within which are disposed roller bearings I8, these roller bearings lying between the race-ways and the periphery of the pin II and particularly that portion termed llb. This construction takes care of the end thrust on the rollers. The side thrust is taken care of by ball bearings I9 interposed between a race-way 20 and a race-way 2I. The race-way 2| is formed in a collar 22 secured to the pin portion I lb.

In order to assemble the cutter upon the pin portion III), a part of said cutter intermediate a pair of teeth 23 is formed with a bore communicating with the race-way 2| so that the balls I9 may be received between the race-ways 20 and 2|, after which a plug 24 may be welded in place. A thrust washer 25 is placed at one end of the cutter roller and the inner face of the leg 8. A tapered collar 26 may be carried intermediate the pin II for separating ends of the two cutter rollers. Assuming that both cutter rollers are assembled. upon the pin II in the manner just stated for the cutter roller I5, the pin is then secured to the legs 6 and 8 by placing the pin within the slots 9 and then welding the pin in position, the weld being indicated by the dotted line portion for the leg 6, at 21.

The operation, uses and advantages of the invention are as follows:

I may of course provide roller cutters, such as a pair of cutters, one of which is shown attached to the leg I at 2B. When the pin 3 is attached to usual sinker bar and drill pipe and in turn connected to the rotary table in the usual manner, fluid may be circulated through the opening 5 and over the cutters to maintain the cutter teeth clean of debris and to maintain circulation back to the surface of the hole. As the hole grows deeper, any tendency of the operator to drop the load on the teeth to force the cutter through rock formation causes stress not only upon the roller cutters but upon its supporting pin or pins. The bent pin construction, however, acts to directly communicate all bending stress in the pin directly to the legs of the cutter body, and as the cutter body and its legs are formed of very heavy material, there is little likelihood of the pin itself actually bending 01' the cutters getting out of true alignment or from the best position for performing a cutting operation, which position, of course, is that which permits the cutter teeth to properly engage the formation. It the cutters do not properly contact the formation and there is a springing action, the

drill may cause a crooked hole, or break off certain of the cutter teeth. The spacer washer 26 acts to hold the two cutter rollers in an angular position without, however, impeding rotation thereof. End thrust on the cutters is C0nvenient- 1y taken care of by the rollers I8 and side thrust by the balls l9.

It has been found in-actual practice that if a. roller cutter has its teeth broken, that the drill upon removal may easily have a roller replaced by either drilling out the weld 21 or otherwise removing the weld so that the pin may drop from the slotted ends of the legs 6 and 8, whereupon the plugs 24 may be removed to permit removal of the balls 19. The cutter rollers are now free and may be removed from the pin H.

I claim:

In a rock bit construction, a body provided with a pair of legs, a pin bent intermediate its ends and secured at its ends respectively in said legs, a pair of roller cutters carried on said pin at opposite sides of its intermediately bent portion, and a single collar formed on said pin at its intermediate bent portion for engaging and maintainin the inner ends of said rollers in slightly spaced relation.

HERMAN C. SMITH. 

